1. Technical Field
The present invention relates to a recording method for recording images or the like on a recording medium using liquid such as ink.
2. Related Art
As a recording apparatus that performs a recording process on a recording medium using liquid, an ink jet recording apparatus (hereinafter, referred to simply as “recording apparatus”) that ejects ink onto a recording sheet is generally known. Such a recording apparatus is provided with a transport mechanism that transports the recording sheet along a transport direction and a recording head that ejects ink onto the recording sheet being transported to an inside of the apparatus by the transport mechanism. Upon receiving image data from a host computer connected to the recording apparatus, the recording apparatus causes the recording head to eject various types of ink onto the recording sheet so that images based on the image data are recorded on a recording area of the recording sheet.
The recording sheet on which images are recorded is likely to be expanded or contracted by the influence of an installation atmosphere (particularly, humidity) of the recording apparatus, the ejected ink or the like. Moreover, in some cases, the recording sheet is transported by the transport mechanism in a state of being oblique to the transport direction. In such a case, the recording head may be unable to eject ink at an appropriate position of the recording sheet. As a solution to such a problem, JP-A-2004-142269 proposes a recording method.
According to the recording method disclosed in JP-A-2004-142269, when recording of images on the recording sheet is completed for the first page, a gap (i.e., a margin gap) between an end of a recording area of the recording sheet on which the recording has been performed and an end of the recording sheet is measured, and a difference between the measured gap and a predetermined gap which is preliminarily set as a recording condition. When images are recorded on the second or subsequent page of the recording sheet, the recording is performed on the recording sheet in a state where the ejection state of ink on the recording sheet is corrected in accordance with the difference. Therefore, even when the recording sheet is expanded or contracted or the recording sheet is transported in an oblique state, images are appropriately recorded on the recording sheet.
However, among recording apparatuses, there is known a line head type recording apparatus in which a plurality of recording units (for example, two recording units) having a length equal to or greater than the length of the recording sheet in the width direction is arranged to be separated from each other in the transport direction. Among these recording units, an upstream recording unit disposed on the upstream side in the transport direction is configured to be able to eject first types of ink (for example, cyan ink and magenta ink) and a downstream recording unit disposed on the downstream side in the transport direction is configured to be able to eject second types of ink (for example, yellow ink and black ink). In such a recording apparatus, after the first types of ink are ejected from the upstream recording unit onto the recording sheet, the second types of ink are appropriately ejected from the downstream recording unit onto the recording sheet so that the landing position of the second types of ink overlaps with the landing position of the first types of ink from the upstream recording unit.
At this time, portions of the recording sheet on which the ink has been landed may be locally expanded due to the ink ejected onto the recording sheet by the upstream recording unit. In such a case, a positional deviation may occur which is a positional difference between the landing position of the ink from the upstream recording unit and the landing position of the ink from the downstream recording unit which ejects ink later than the upstream recording unit. To solve such a problem, a technique that correct at least one of the landing position of the ink from the upstream recording unit and the landing position of the ink from the downstream recording unit to thereby achieving an improvement in the quality of images recorded on the recording sheet has recently been proposed.
However, the content of moisture (i.e., solvent or dispersion medium) in the recording sheet to which ink is ejected may differ at each position where the ink ejection states are different. Therefore, an expansion state of a portion of the recording sheet in which the moisture content is large may differ from an expansion state of a portion in which the moisture content is small. As a result, in the recording sheet for which recording has been performed, the degree of expansion/contraction resulting from vaporization of the moisture may become uneven at each position of the recording sheet. Since the degree of expansion/contraction differs at each position of the recording sheet, in order to correct the landing positions of the respective types of ink in such recording sheet, it is necessary to perform very complicated control.